LEASES - Lease Cost (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 27, 2020 USD ($)	Jun. 27, 2020 USD ($)
Leases [Abstract]
Operating lease costs	$ 2,314	$ 4,611
Finance lease cost - amortization of right-of-use assets	53	106
Finance lease cost - interest on lease liabilities	17	34
Short-term lease cost	49	104
Variable lease cost	816	1,654
Sublease income	185	371
Total lease cost	$ 3,064	$ 6,138
Weighted average remaining lease term:
Operating leases	6 years 7 months 17 days	6 years 7 months 17 days
Finance leases	4 years 2 months 4 days	4 years 2 months 4 days
Weighted average discount rate:
Operating leases	6.61%	6.61%
Finance leases	6.24%	6.24%